Efficient and green oxidative degradation of methylene blue using Mn-doped ZnO nanoparticles (Zn1−xMnxO)

Mn-doped ZnO nanoparticles, Zn_1?xMn_xO, were synthesised by a polyethylene glycol (PEG) sol–gel method and the physicochemical properties of compounds were characterised by atomic absorption spectroscopy (AAS), energy-dispersive X-ray analysis, X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The catalytic degradation of an organic dye, methylene blue (MB), in the presence of Zn_1?xMn_xO as the catalyst and hydrogen peroxide (H₂O₂) as the oxidant at room temperature in water has been studied. Effects of oxidant, catalyst amount, catalyst composition, pH value of the solution and an OH-radical scavenging agent on the degree of the decomposition of MB dye were also studied.     

Tunable structure,morphology of Zn1−xMgxO fine powder prepared by spray pyrolysis method and its luminescence properties

In this report, the role of Magnesium on the crystal structure, morphology, and its luminescence properties of Zn_1−xMg_xO particle were investigated. The Zn_1−xMg_xO particle was prepared by spray pyrolysis method. The obtained particle was analyzed using XRD, SEM-EDS, and photoluminescence spectroscopy correspondingly for crystal structure, morphology and elemental analysis, and photoluminescence properties due to the presence of magnesium dopant. The XRD results showed that the original structure of the particle is hexagonal wurtzite and change to cubical as the increase of Mg. The a- lattice parameter increased, and c- lattice parameter decreased with increasing the concentration of Mg in wurtzite crystal. The SEM results exhibited different morphology of the resulting particle. The morphology of the sample is dense with wrinkled shape and is changing to spherical as the result of Mg incorporation into the crystal. Photoluminescence study revealed that the addition of Mg affects the existence of new energy state beside native defect of ZnO in between valence and conduction band. The widening of bandgap on Zn_1−xMg_xO is due to the blue shift of excitonic peak in the excitation spectrum that usually called Burstein-Moss effect.     

Synthesis of cactus-like zincoxysulfide (ZnOxS1−x) nanostructures assisted by a task-specific ionic liquid and their photocatalytic activities

A hydrothermal method has been employed to prepare cactus-like zincoxysulfide ZnO_xS_1?x nanostructures with the assistance of a dicationic task-specific ionic liquid (TSIL), [mim]{(CH)₂}₃[imm](SCN)₂. To the best of our knowledge, this is the first time that this TSIL with the SCN anion has been used in place of conventional reagents as a source of S to prepare a ZnO_xS_1?x nanostructure. The photocatalytic activities of the ZnO_xS_1?x nanostructures have been compared using UV and visible lights. BET results showed that the surface areas and photocatalytic activities of cactus-like zincoxysulfide ZnO_xS_1?x nanostructures were higher than those of other samples. ZnO_xS_1?x nanostructures with cactus-like morphology exhibited a significant enhancement of photocatalytic activity toward the degradation of methyl orange (MO) as compared to other samples, as revealed by photoluminescence measurements. This could be attributed to enhanced oxygen vacancies and crystallite defects formed as a result of substitution of S^2? in the lattice of ZnO.     

Adsorption and photocatalysis of nanocrystalline TiO2 particles prepared by sol–gel method for methylene blue degradation

Titanium dioxide (TiO₂) powders were synthesized by using TiO₂ colloidal sol prepared from titanium-tetraisopropoxide (TTIP) and used as a starting material by applying the sol–gel method. The effect of aging times and temperatures on physical and chemical properties of TiO₂ sol particles was systematically investigated. The results showed that the crystallinity and average particle size of TiO₂ can be successfully controlled by adjusting the aging time and temperature. The samples after calcination of TiO₂ powders were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), and nitrogen adsorption measurements. In addition, the photocatalytic activity of synthesized TiO₂ powders was evaluated by studying the degradation of 10 ppm aqueous methylene blue dye under 32 W high pressure mercury vapor lamp with 100 mg of TiO₂ powders. The highest photocatalytic activity was observed in TiO₂ powder synthesized at 90 °C for 0 h attributed to the presence of anatase and rutile phases in an 80:20 ratio.     

Facile and template-free preparation of α-MnO2 nanostructures and their enhanced adsorbability

In this paper, nanostructured MnO₂ materials were successfully prepared through a simple and template-free hydrothermal method. X-ray diffraction pattern indicates that the as-prepared nanomaterials are α-MnO₂. Transmission Electron Microscopy and Scanning Electron Microscopy images demonstrate that nanostructured rod-clusters α-MnO₂ could be evolved from the nanorods. Brunauer-Emmett-Teller (BET) surface area measurement was employed to characterize the surface property. Moreover, the as-obtained (α-MnO₂) nanomaterials could act as an efficient adsorbent to remove Congo Red and Methlylene Blue. More significantly, the nanomaterials are nontoxic and environmentally friendly via biological methylthiazolyldiphenyltetrazoliumbromide assay experiments. Its nontoxic and enhanced adsorbability properties guarantee their safe applications in environmental protection and industrial aspects.     

Nanostructure, optical and photoluminescence properties of Zn1−xNixO nanoclusters by co-precipitation method

Zn_1?xNi_xO (x = 0, 0.01, 0.02, 0.03, 0.04 and 0.05) nanoclusters have been successfully synthesized by co-precipitation method. The synthesized samples have been characterized by powder X-ray diffraction, energy dispersive X-ray spectra, UV–visible spectrophotometer and Fourier transform infrared spectroscopy. The XRD and SEM measurements reveal that the prepared undoped and Ni-doped nanoclusters have different microstructure without changing a hexagonal wurtzite structure. The calculated average crystalline size from XRD measurement decreases from 37.5 to 26.6 nm for x = 0 to 0.05 which was confirmed by SEM micrographs. The change in lattice parameters, micro-strain, shift of XRD peaks and the blue shift of energy gap from 3.18 to 3.33 eV (ΔE_g = 0.15 eV) for Ni = 0–0.02 and red shift of E_g from 3.33 to 3.14 eV (ΔE_g = 0.19 eV) for Ni = 0.02 to 0.05 reveal the substitution of Ni²⁺ ions into Zn–O lattice. The presence of functional groups and the chemical bonding are confirmed by FTIR spectra. The shift of NBE UV emission between 374 and 395 nm, the shift of green band emission between 517 and 531 nm, the change in intensity and the broadening effect in the photoluminescence spectra confirms the substitution of Ni²⁺ ions into the Zn–O lattice. Ni-doped ZnO system shows a great pledge for the fabrication of nano-optoelectronic devices like tunable light emitting diode in the near future.     

Facile preparation of three-dimensional graphene oxide/ $${\iota}$$ ι -carrageenan composite aerogel and its efficient ability for selective adsorption of methylene blue

Journal of Materials Science - A three-dimensional graphene oxide/ $${\iota}$$ -carrageenan composite aerogel (GO/ $${\iota}$$ -Car) has been facilely manufactured in a benign approach and...     

UV–LED driven photodegradation of organic dye and antibiotic using strontium titanate nanostructures

Journal of Materials Science: Materials in Electronics - In the present study, SrTiO3 (strontium titanate) photocatalyst was prepared through the hydrothermal process for photodegradation of...     

Photoelectric properties of undoped and lithium-doped Zn1−xMgxTe alloys

The room temperature photoelectric response of undoped and lithium-doped Zn_1–xMg_xTe (0 x 0.50) alloys has been measured in the wavelength range 0.50 3.0 m. The response curve for undoped samples is characterized by a single peak in the band edge region. The peak shifts with composition in accordance with the expected shift in the energy band gap. Lithium-doped samples show an additional peak centred at 1.04 eV for all compositions. This peak is attributed to photo-generated holes in the split-off band created as the result of electronic transitions to shallow acceptor impurities.     

Potato starch-assisted green synthesis of nanoferrite and ferrite–semiconductor nanocomposites for effective visible light photocatalytic degradation of methylene blue

Journal of Materials Science - Biodegradable potato starch-assisted nanoferrite and ferrite–semiconductor nanocomposites have been synthesized by the co-precipitation method for the...     

Optical emission and absorption spectra of Zn–ZnO core-shell nanostructures

The core-shell Zn–ZnO nanostructures were fabricated from Zn-powder embedded in graphite (i.e. carbon matrix) in a thin-films form by an inexpensive vacuum arc technique followed by laser ablation. The grazing incidence X-ray diffraction pattern shows that intensity of Zn-peak decreases, and subtle ZnO-peak increasing with the increase in laser power. The high resolution transmission electron microscopic study clearly exhibits the formation of a core-shell nanostructure as fabricated by laser ablation. The emission characteristics of laser ablated (with different powers) samples show a strong exciton peak at 388 nm, and a few more weak peaks (due to weak defect states in the visible range). The optical absorption spectra were obtained from the excitonic peaks (from 344 nm to 317 nm) on decreasing laser power. These peaks occur due to the coupling of exciton absorption (from ZnO shell layer) and core metal interband absorption. The Zn–ZnO core-shell nanostructure is useful for nanophotonic applications.     

Construction of TiO₂ hierarchical nanostructures from nanocrystals and their photocatalytic properties

Anatase TiO(2) mesoporous structures with high specific surface areas are of special significance in various applications. In this work, hierarchical anatase TiO(2) materials with flowerlike morphologies have been prepared via a one-step template-free hydrothermal method, by using titanocene dichloride as precursor and EDA as chelating agent in aqueous solution. Particularly, the hierarchical structures are assembled from very thin TiO(2) nanosheets, which are composed of numerous highly crystallized anatase nanocrystals. In addition, the assembled materials own relatively large specific surface areas of 170 m(2)/g, and uniform mesopores of 7 nm. We further demonstrate that the hierarchical TiO(2) materials show very good photocatalytic performance when applied in photodegradation of methylene blue, which should be related to the unique features of hierarchical structures, large specific surface areas and high crystallization degree of the obtained TiO(2) materials. With these features, the hierarchical TiO(2) may find more potential applications in the fields such as dye-sensitized solar cells and lithium ion batteries.     

In situ incorporation of well-dispersed Cu–Fe oxides in the mesochannels of AMS and their utilization as catalysts towards the Fenton-like degradation of methylene blue

Multi-components active metal oxide-supported catalysts are highly promising in heterogeneous catalysis due to some special promoting effects. In this study, by the controllable amount of Cu, Cu–Fe decorated anionic surfactant-templated mesoporous silica (Cu _x Fe/AMS) was directly prepared. The obtained catalysts were characterized by X-ray diffraction, N₂ adsorption–desorption, inductively coupling plasma emission spectroscopy, scanning electron microscopy, transmission electron microscopy, UV–visible, hydrogen temperature-programmed reduction, and X-ray photoelectron spectroscopy techniques. The results revealed that bimetallic Cu–Fe oxides were directly formed and highly dispersed in the mesochannels during the calcinations and the introduction of Cu²⁺ and Fe²⁺ on the micelles has influence on the structure properties. As compared to the monometallic Fe-modified AMS, the presence of Cu promotes the effects between Fe species and silica wall, leading to the better dispersion of Fe in the mesochannels of AMS. Finally, a series of Cu–Fe-modified AMS were used as Fenton-like catalysts and exhibited good catalytic activity in the degradation of methylene blue (MB), which resulted from high dispersion of Fe species and synergetic effect between Cu and Fe active sites. 1.0 was the optimum molar ratio of Cu²⁺ to Fe²⁺ ions to achieve the best catalytic activity and stability.     

Effect of Mg2+ ions substitution on phase formation,structural, morphological,and optical properties of Zn0.1−xMgxO structure

Journal of Materials Science: Materials in Electronics - In the present research work, Mg-doped zinc oxide Zn0.1?xMgxO (For x?=?0.000, 0.002, 0.006, 0.010) nanoparticles were...     

Facile synthesis of uniform ZnxCd1−xS alloyed hollow nanospheres for improved photocatalytic activities

In this work, we demonstrate that a facile template-free method has been developed for the fabrication of uniform Zn_xCd_1?xS (0 ≤ x ≤ 1) alloyed hollow nanospheres. The as-prepared Zn_xCd_1?xS hollow nanospheres have been investigated by X-ray powder diffraction, field-emission scanning electron microscopy (JEOL-6700F) and transmission electron microscopy (JEOL 3010), respectively. The research results indicate that the as-prepared Zn_xCd_1?xS hollow nanospheres are with an average diameter of 80 and 30 nm in shell thickness. As expected, the as-prepared Zn_0.5Cd_0.5S alloyed hollow nanospheres show improved photocatalytic performance towards photodegradation of Rhodamine B. These findings may open new opportunities for the design of effective, stable, and easy-recyclable photocatalytic materials.